This invention relates to an efficacious combination of a zinc salt and an isothiocyanate, and more particularly to an oral composition containing such combination which exhibits increased oral care effects against volatile sulfur compounds (VSCs).
Oral malodor or “halitosis” used herein relates to bad breath caused by physiologic (transient or temporary) and/or pathologic conditions. Physiological causes of halitosis include: halitosis caused by deleterious habits, morning breath, and xerostomia (dry mouth). Pathological causes for halitosis include: secondary or oral tissue conditions associated with gingival and periodontal diseases, acute necrotizing ulcerative gingivitis, residual post-operative blood, debris under dental appliances, ulcerative lesions of the oral cavity, coated tongue, xerostomia, salivary gland diseases and Tonsilloliths (tonsil stones).
Oral malodors are produced mainly due to the breakdown of proteins into individual amino acids, followed by the further breakdown of certain amino acids to produce detectable foul gases. The oral cavity provides a positive growth environment for gram-negative anaerobes that metabolize proteins as an energy source via breakdown of proteinaceous substrates from impacted food particles and sloughed off oral cellular debris. Often, inflammation causes these cells to be shed at a faster rate than the saliva can cleanse. Bacterial action then hydrolyzes the proteins to amino acids; and the amino acids that contain sulfur functional groups, methionine and cysteine, serve as precursors to volatile sulfur compounds (VSCs).
These gaseous volatile sulfur compounds (VSCs) are responsible for oral malodor, and consist primarily of hydrogen sulfide (H2S), methyl mercaptan (CH3SH) and dimethyl sulfide [(CH3)2S]. For example, amino acids methionine and cysteine are reduced to hydrogen sulfide and methyl mercaptan, respectively, in the presence of sulfhydrase-positive microbes. Methyl mercaptan has been found to be the main component of tongue dorsal surface malodor in patients with periodontal disease, whereas hydrogen sulfide predominates in orally healthy subjects.
Although bad breath primarily represents a source of embarrassment or annoyance, the VSCs most responsible for halitosis are also potentially damaging to the tissues in the mouth, and can lead to periodontitis (inflammation of the gums and ligaments supporting the teeth). In particular, VSCs have been found to damage the collagen and proteoglycan components in connective tissue by cleaving disulfide bonds. This de-aggregation of the extracellular matrix allows microbes to permeate the oral mucosa. As bacteria further accumulates in pockets that form next to the teeth, periodontal disease progresses, as well as halitosis. If the periodontal disease advances significantly, overall systemic health may be jeopardized; for example, periodontal bacterial by-products can enter the blood stream and may result in heart disease, stroke and under-weight babies at birth.
For the treatment of oral malodor, the public has increasingly turned to commercially available mouth-freshening products. The market for these products has been growing continuously as sufferers from chronic oral malodor experience personal discomfort and social embarrassment.
Various compounds such as chlorine dioxide, sodium chlorite, and metal salts such as zinc and copper have been used as VSC neutralizing agents in a variety of oral compositions. Such compounds have been provided and are available today as mouthwashes and rinses for the prevention and/or treatment of oral malodor. In general, many of the oral rinses available today are used for the prevention and/or treatment of oral malodor or halitosis, but for chronic bad breath, many rinses offer little to no help.
While being effective in fighting oral malodor, compounds such as chlorine dioxide, sodium chlorite, and metal salts such as zinc and copper impart strong, unpleasant flavors and aromas thereby negatively impacting taste and deterring use. Often, mouth rinses incorporating these compounds can also cause some generalized irritations to the oral cavity such as desquamation, ulceration, and inflammation. Moreover, oral compositions incorporating these compounds (other than mouthwashes and rinses) which are retained in the mouth for longer periods of time, such as chewing gums, mints, and lozenges, further enhance irritations to the oral cavity when these compounds are employed.
Alternatively, isothiocyanates can also act as a reagent to remove both intrinsic and extrinsic VSC's, either by conversion of sulfur groups (SH) into the water soluble dithiocarbamate or by formation of the less volatile disulfide. Unfortunately at certain concentrations, isothiocyanates possess a pungent or irritating odor, and sharp bitter taste. Because of the unpleasant organoleptic attributes, using isothiocyanates in oral compositions is difficult.
In view of the preceding challenges, there is a continued need to develop an effective treatment for oral malodor caused by physiologic and/or pathologic conditions. Accordingly, the dental community, as well as the general public, are continuously seeking efficacious, commercially available, and organoleptically pleasing oral compositions to reduce various types of bad breath (halitosis), including occasional, chronic, or at specific times of the day.
Thus, it would be highly advantageous, to have an efficacious, commercially available, and organoleptically pleasant product solution for oral malodor.